More than 20 years ago, there was another C-like compiler for Flat Real Mode[0] called BFlat[1][2]. I want to say there are other tools called BFlat or some near variant.

[0] https://en.wikipedia.org/wiki/Unreal_mode

[1] http://www.lanet.lv/simtel.net/msdos/misclang-pre.html

[2] http://www.lanet.lv/ftp/simtelnet/msdos/misclang/bflat050.zi...